Request for advice: Aerobatics and GPS

ArduPlane
1

Hi all, I’m new here, so please forgive any breaches of protocol…

I am trying to develop a traction kite for a boat. It will really be a rigid tethered glider. I want to use GPS and barometry to track the position of the kite.

The kite needs to fly in a figure-8 pattern. And since it’s tether needs to be close to horizontal, the figure-8 will be roughly vertical. The time to fly one figure-8 will be around 40 seconds.

So the glider will be aerobatic. Question is, how can I maintain continuous GPS position during such manoeuvering. Clearly, a GPS antenna fixed inside the glider will not always be pointing up.

Can this be done?

I can think of 3 possible ways:

  1. Use multiple GPS units. But will a GPS unit get a fix quickly when its antenna comes to see the sky?
  2. Rotate the antenna using servos. Like camera pan & tilt.
  3. Let inertial guidance fill in the gaps.

Is there any established wisdom on this question? I’m noticing some material on full-size aerobatics which seems to say you can’t trust GPS.

I’d appreciate any input… Tridge? Others?

  • Geoff Draper, Orbost, Vic 3888.
2

U-Blox reference text about Antenna: https://www.u-blox.com/sites/default/files/products/documents/GNSS-Antennas_AppNote_%28UBX-15030289%29.pdf

Helical antenna could help. I’m using Flight Coach https://www.flightcoach.org/ and it show GPS glitch when orientation is poor

Capture d’écran 2022-01-30 à 08.28.52

3

Hi mlebret,

Thank you for those links. Both really interesting. However I think I need to brush up on my antenna theory to properly understand the first one. I think I can feel another MOOC coming on…

I’ll feedback some more when I’ve investigated some more.

  • Geoff